1. Field of the Disclosure
The present disclosure relates to level shifters and more specifically to low voltage level shifters.
2. Description of the Related Art
Different logic blocks inside an integrated circuit can function using different supply voltages. For instance, a core logic block can use a low voltage power supply (Vdd) to reduce power consumption, while an input/output (I/O) logic block can use a high voltage power supply (Vdde) to communicate to components outside of the integrated circuit. A level shifter is used to interface two logic blocks operating with different voltage power supplies.
In order for a level shifter to operate, the active voltage level of the input signal has to be greater than the threshold voltage of the switching devices (e.g., transistors) receiving the input signal. If the active voltage level of the input signal is not greater than the threshold voltage, the switching devices receiving the input signal are not turned on, despite the active logic state of the input signal. As power consumption in integrated circuits becomes increasingly important, attempts are being made to lower the supply voltage of core components.
Such decrease in supply voltage may also lower the level of input signal and cause switching devices to turn off even when the input signal is in an active logic state.